06-28-2020, 05:24 PM
I don't suppose you have either the UART adapter, or a spare USB to 3.3V TTL serial adapter and spare audio cable laying around, do you?
The boot messages over the serial port would really help hammer down the details of what is failing, where. Given that you at least occasionally get some display output, it's probably not dead, though a bad SD card slot wouldn't be out of the question. Have you tried blowing it out with some duster canned air in case there's some grit in there?
Without serial output, though, it's really hard to troubleshoot this sort of thing. The system is "blind" on the display until an awful lot of stuff is up and running, with the status LED being the only indicator - and it's not an amazing indicator.
At power-on, the boot ROM will look for the various other firmware binaries on the internal SPI, the eMMC, then the SD card.
Once the firmware is loaded, it will (typically) try to boot from the SD card, then eMMC. There are some firmware packages out that will boot from NVMe and supposedly USB, but they have to be on the SPI flash to do that, and unless you've gone out of your way to install one of those, they aren't installed.
Even if your SD card slot has failed, you should still be able to use the machine if you get a good image on the eMMC. You'd need the USB to eMMC adapter for that - and if you're ordering one, get a headphone-jack-UART adapter too (or just build one).
Or, if you're beyond frustrated with it and based in the US, I'm halfway interested in another PBP to use as a firmware dev target. It's really quite hard to develop firmware on the same system you're trying to target... though I'd prefer something with a working SD card slot for that, based on the boot process.
The boot messages over the serial port would really help hammer down the details of what is failing, where. Given that you at least occasionally get some display output, it's probably not dead, though a bad SD card slot wouldn't be out of the question. Have you tried blowing it out with some duster canned air in case there's some grit in there?
Without serial output, though, it's really hard to troubleshoot this sort of thing. The system is "blind" on the display until an awful lot of stuff is up and running, with the status LED being the only indicator - and it's not an amazing indicator.
At power-on, the boot ROM will look for the various other firmware binaries on the internal SPI, the eMMC, then the SD card.
Once the firmware is loaded, it will (typically) try to boot from the SD card, then eMMC. There are some firmware packages out that will boot from NVMe and supposedly USB, but they have to be on the SPI flash to do that, and unless you've gone out of your way to install one of those, they aren't installed.
Even if your SD card slot has failed, you should still be able to use the machine if you get a good image on the eMMC. You'd need the USB to eMMC adapter for that - and if you're ordering one, get a headphone-jack-UART adapter too (or just build one).
Or, if you're beyond frustrated with it and based in the US, I'm halfway interested in another PBP to use as a firmware dev target. It's really quite hard to develop firmware on the same system you're trying to target... though I'd prefer something with a working SD card slot for that, based on the boot process.